- Mills, Evan, Hannah Friedman, Tehesia Powell, Norman Bourassa, David Claridge, Tudi Haasl and Mary Ann Piette, LBNL-56637, December 2004.
Building performance problems are pervasive. Deficiencies such as design flaws, construction defects, malfunctioning equipment, and deferred maintenance have a host of ramifications, ranging from equipment failure, to compromised indoor air quality and comfort, to unnecessarily elevated energy use or under-performance of energy-efficiency strategies. Fortunately, an emerging form of quality assurance—known as building commissioning—can detect and remedy most deficiencies.
Scattered case studies and anecdotal information form the basis of the conventional wisdom among energy-management professionals that commissioning is highly cost-effective. However, given the lack of standardized information on costs and benefits of detecting and correcting deficiencies, it is perhaps of no surprise that the most frequently cited barrier to widespread use of commissioning is decision-makers' uncertainty about its cost-effectiveness.
Designed as a "meta-analysis", this report compiles and synthesizes extensive published and unpublished data from buildings commissioning projects undertaken across the United States over the past two decades, establishing the largest available collection of standardized information on commissioning experience. We analyze results from 224 buildings across 21 states, representing 30.4 million square feet of commissioned floor area (73 percent in existing buildings and 27 percent in new construction). These projects collectively represent $17 million ($2003) of commissioning investment. The new-construction cohort represents $1.5 billion of total construction costs.
We develop a detailed and uniform methodology for characterizing, analyzing, and synthesizing the results. For existing buildings, we found median commissioning costs of $0.27/ft2, whole-building energy savings of 15 percent, and payback times of 0.7 years. For new construction, median commissioning costs were $1.00/ft2 (0.6 percent of total construction costs), yielding a median payback time of 4.8 years (excluding quantified non-energy impacts).
These results are conservative insofar as the scope of commissioning rarely spans all fuels and building systems in which savings may be found, not all recommendations are implemented, and significant first-cost and ongoing non-energy benefits are rarely quantified. Examples of the latter include reduced change-orders thanks to early detection of problems during design and construction, rather than after the fact, or correcting causes of premature equipment breakdown. Median one-time non-energy benefits were -$0.18/ft2-year for existing buildings (10 cases) and -$1.24/ft2-year for new construction (22 cases)—comparable to the entire cost of commissioning.
Deeper analysis of the results shows cost-effective outcomes for existing buildings and new construction alike, across a range of building types, sizes and pre-commissioning energy intensities. The most cost-effective results occurred among energy-intensive facilities such as hospitals and laboratories. Less cost-effective results are most frequent in smaller buildings. Energy savings tend to rise with increasing comprehensiveness of commissioning.
The projects identify 3,500 deficiencies (11 per building, 85 projects reporting) among existing buildings and 3,305 (28 per building, 34 projects reporting) among new construction. HVAC systems present the most problems, particularly within air-distribution systems. The most common correctional measures focus on operations and control.
There are material differences between our results for existing buildings and new construction. This can be seen in the "bottom-line" results per unit floor area—six-fold greater energy savings and four-fold lower commissioning costs for existing buildings. It should be noted, however, that median payback times are attractive in both cases, especially when non-energy impacts are accounted for. Larger median building floor areas in our existing-buildings sample (151,000 square feet) tended to favor lower costs compared to the new-construction cases (69,500 square feet). New-construction commissioning is more strongly driven by non-energy objectives such as overall building performance, thermal comfort, and indoor air quality, whereas existing-building commissioning is more strongly driven by energy savings objectives. The need for commissioning in new construction is indicated by our observation that the number of deficiencies identified in new-construction exceed that for existing buildings by a factor of three.
Some view commissioning as a luxury and "added" cost, yet it is only a barometer of the cost of errors promulgated by other parties involved in the design, construction, or operation of buildings. Commissioning agents are just the "messengers"; they are only revealing and identifying the means to address pre-existing problems.
We find that commissioning is one of the most cost-effective means of improving energy efficiency in commercial buildings. While not a panacea, it can play a major and strategically important role in achieving national energy savings goals—with a cost-effective savings potential of $18 billion per year or more in commercial buildings each year across the United States. Commissioning is under-attended in public-interest deployment programs as well as research and development activities. As technologies, controls, and their applications change and/or become more complex in an effort to capture greater energy savings, the risk of under-performance will rise and with it the value of commissioning. Indeed, innovation driven by the desire for increased energy efficiency may itself inadvertently create energy waste if those systems are not designed, implemented, and operated properly. The ultimate impact of energy efficiency research and development portfolios, as well as deployment programs, lies in no small part in the extent to which they are coupled with cost-effective quality assurance.